In this task, you are given an article. Your task is to summarize the article in a sentence.

Example Input: Avijit Roy, an atheist who advocated secularism, was attacked as he walked back from a book fair with his wife, who was also hurt in the attack.
No-one has been arrested but police say they are investigating a local Islamist group that praised the killing.
Hundreds of people gathered in Dhaka to mourn the blogger's death.
Mr Roy's family say he received threats after publishing articles promoting secular views, science and social issues on his Bengali-language blog, Mukto-mona (Free Mind).
He defended atheism in a recent Facebook post, calling it a "rational concept to oppose any unscientific and irrational belief".
His Mukto-mona website on Friday bore the message in Bengali "we are grieving but we shall overcome" against a black background.
US State Department spokeswoman Jen Psaki described it as an assault on Bangladesh's proud tradition of free intellectual and religious speech.
A group of men ambushed the couple, who live in the US and were visiting Dhaka only to attend the book festival, as they walked toward a roadside tea stall.
At least two of the attackers hit the couple with meat cleavers in the attack on Thursday evening, police chief Sirajul Islam told AP news agency.
Dropping their weapons, the attackers ran away, disappearing into the crowds.
Police told the BBC they were investigating a local hard-line religious group that had praised the killing in an online message.
Ajay Roy, father of the dead man, urged the authorities to find the killers and "ensure exemplary punishment".
"This Bangladesh which was built  by the blood-sacrifice of the martyrs has now turned into a den of militants," he said.
Students, teachers and bloggers gathered at Dhaka University on Friday to protest against the killing.
In a forthcoming article to be published in the Free Inquiry magazine of April-May 2015, Mr Roy likens religious extremism to a "highly contagious virus".
He says he received threats from Islamist hardliners in Bangladesh last year when his book, The Virus of Faith, was released at a book fair.
"The death threats started flowing to my e-mail inbox on a regular basis," he writes.
"I suddenly found myself a target of militant Islamists and terrorists. A well-known extremist... openly issued death threats to me through his numerous Facebook entries.
"In one widely circulated status, he writes, 'Avijit Roy lives in America and so, it is not possible to kill him right now. But he will be murdered when he comes back.'"
The killing in early 2013 of another secular blogger, Ahmed Rajib Haider, which was blamed on religious hardliners, sparked protests from free-speech supporters and counter-protests from Islamists.
The police say the attack on Mr Roy was similar to the 2013 murder.
Avijit Roy
Death threats against atheist writers and bloggers are nothing new in Bangladesh.
Prominent writer Taslima Nasreen had to leave Bangladesh after she received death threats from hard-line Islamists in the mid-1990s.
She wrote on her blog: "Avijit Roy has been killed the way other free thinker writers were killed in Bangladesh. No free thinker is safe in Bangladesh.
"Islamic terrorists can do whatever they like. They can kill people with no qualms whatsoever."
Example Output: Attackers in the Bangladeshi capital Dhaka have hacked to death a US-Bangladeshi blogger whose writings on religion angered Islamist hardliners.

Example Input: Lebanon now has "the highest per capita concentration of refugees worldwide", said the head of the UN refugee agency.
"For Lebanon, a small nation beset by internal difficulties, the impact is staggering," he added.
About 9.5 million people, almost half of Syria's population, have fled their homes since the start of the conflict.
More than 2.5 million have fled the country, with large numbers being taken in by Turkey, Jordan, Iraq, Egypt and others.
However Lebanon is bearing the biggest burden of all - the number of Syrian refugees there now amount to a quarter of the local population.
By Jim MuirBBC News, Beirut
Everybody knows that the real number of Syrian refugees in Lebanon is already well past the million mark, but the fact that that many have now been officially registered is yet another grim milestone as the conflict grinds on.
Lebanon's the smallest and most vulnerable of Syria's neighbours, yet it's taken in by far the largest number of refugees - one for every four of the country's own people.
That's a huge strain - the foreign minister said last month that it threatened Lebanon's very existence, and it's growing all the time, with about 2,500 new refugees being registered every day.
The UN has only received 14% of the funding it's asked for. That means that relief has to be cut back and carefully targeted to the most needy.
The BBC's Jim Muir in Beirut says this is a huge strain for Lebanon, the smallest and most vulnerable of Syria's neighbours.
Last month the Lebanese foreign minister said the crisis was "threatening the existence" of his country.
"The Lebanese people have shown striking generosity, but are struggling to cope," Mr Guterres said.
The UN's refugee agency, UNHCR, notes that the influx of refugees is accelerating.
"Every day, UNHCR in Lebanon registers 2,500 new refugees: more than one person a minute," the agency said in a statement.
International aid agencies are finding it increasingly difficult to cope with the flow of refugees.
UNHCR has only received 14% of the $6.5bn (Â£4bn; 4.7bn euros) funding it has asked for.
The hardships many refugees are facing was dramatically highlighted last week when a mother with a sick husband and four children set fire to herself in protest at not receiving help. She was critically injured.
The civil war in Syria between Sunni-led rebels and the government of Bashar al-Assad has also fuelled sectarian tensions in Lebanon, which has a large Sunni and Shia Muslim population.
Hundreds of people in Beirut and other parts of the country have been killed in violence between opponents and supporters of President Assad.
Example Output: The number of refugees who have fled Syria and registered in Lebanon has surpassed the "devastating milestone" of one million, the UN says.

Example Input: Williams, 34, double-faulted on match point to lose 6-2 7-6 (7-5), and Pliskova will face German second seed Angelique Kerber in the final.
The result guarantees that Kerber will overtake Williams at the top of the rankings after the US Open.
Williams had also hoped to win an Open-era record 23rd major singles title.
She remains tied with Steffi Graf for both Grand Slam titles, and the WTA record of 186 successive weeks as world number one.
"Karolina played great today," said Williams, who revealed she had been hampered by a sore left knee since earlier in the tournament
"I think if she had played any less then maybe I would have had a chance. So I think I wasn't at 100%, but I also think she played well. She deserved to win today."
Australian Open champion Kerber beat Denmark's Caroline Wozniacki 6-4 6-3 to reach her first US Open final.
"It's just incredible, it's a great day," said Kerber. "To be here in the final for the first time means a lot and to be number one in the world - it sounds amazing."
Pliskova went into the match on a 10-match winning streak, and with the most aces on the WTA Tour this year, and it was that shot which carried the Czech to victory.
It took Williams 50 minutes to earn her first break point as the Czech nullified her returns, while attacking the American's second serve.
That brought Pliskova two breaks as she raced through the first set in just 26 minutes, and the home crowd on Arthur Ashe Stadium urged on Williams as the six-time champion fell behind midway through the second set.
Williams sparked into life, finally breaking Pliskova's serve - to love - but the anticipated comeback was cut short in the tie-break.
There were a few signs of nerves as Pliskova let a 3-0 lead slip but from 5-4 in front, Williams produced a forehand wide, a backhand long and a double fault to end with 31 unforced errors.
"I don't believe it," said Pliskova, who had never made it past the third round of a Grand Slam in 17 prior attempts.
"I knew I had the chance to beat anyone if I played my game. I am excited to be in the final and to beat Serena as she is such a great champion.
"Even when she was down a set and break she was still fighting. I had to fight hard to win."
Pliskova saved a match point against Venus Williams in round four and becomes only the fourth woman to beat both Williams sisters in the same Grand Slam tournament.
Russell Fuller, BBC tennis correspondent: "This was a nerveless and brilliant all-round performance by Pliskova, who - despite her success on tour - had not made it past the third round of a Grand Slam before this US Open.
"She has a big serve, and she used it, but also returned superbly throughout.
"The confidence gained from saving a match point to beat Venus Williams on the same court, in front of a similarly partisan crowd, in the fourth round helped Pliskova enormously.
"If she wins the final, there will have been four different Grand Slam champions in the women's singles in 2016."
Kerber, 28, was asked about her new-found number one status as she headed to court for the second semi-final, but said: "I'm just thinking about this match."
That appeared the case as she raced into a 4-0 lead after just 16 minutes, her aggression from the baseline too much for Wozniacki, a former world number one now down at 74th in the rankings.
The Dane, 26, grabbed a foothold in the contest and there appeared to be a real edge between the two players, with Kerber complaining at length to the umpire about the noise emanating from Wozniacki's player box.
Wozniacki saved two set points with backhand winners, but Kerber then served it out and powered into a 5-1 lead in the second that all but secured victory.
There was a final flurry of resistance from Wozniacki, who strung together nine points in a row to cut the deficit, before Kerber closed it out to become the 22nd WTA number one - and Germany's second following Steffi Graf.
"For me, it's just amazing to be, after Steffi, the next number one player in Germany," said Kerber. "Steffi's a great player and a great person, and I think she's proud of me, to be the next one after her."
Example Output:
Czech 10th seed Karolina Pliskova outplayed Serena Williams to reach the US Open final and end the American's reign as world number one.

